Modeling of CO2 absorption in membrane contactors

A comprehensive two-dimensional mathematical model was developed for the transport of carbon dioxide through hollow fiber membrane (HFM) contactors. The model was based on “non-wetted mode” in which the gas mixture filled the membrane pores for countercurrent gas–liquid contact. Laminar parabolic velocity profile was used for the gas flow in the tube side; whereas, the liquid flow in the shell side was characterized by Happel's free surface model. Axial and radial diffusion inside the fiber, through the membrane, and within the shell side of the contactor were considered in the model. Moreover, the model was validated with the experimental results obtained for carbon dioxide removal from CO2/CH4 gas mixture using polypropylene membrane contactor with distilled water as the liquid solvent. The modeling predictions were in good agreement with the experimental results for different values of gas and liquid flow rate, gas to liquid ratio, and temperature.